Invasive Alien Species: their impacts on ecosystems and human well-being

Invasive alien species (IAS) are plants, animals, fungi, or pathogens, that are introduced through human activities to areas outside their natural range; and subsequently spread and threaten native species and ecosystem services. We know from the IUCN Red List of Threatened Species^TM[2] that IAS contribute to 60% of recorded global extinctions and are the only driver in 16% of extinctions. Impacts from IAS can be particularly serious in places that are sensitive to their impacts, such as islands or freshwater systems. IAS also have major negative impacts upon human well-being, including health, food security and economies. Unfortunately, due to the rate of introduction of new IAS is showing no sign of slowing down.

An example is the North American beaver (Castor canadensis) an ecosystem engineer that fells trees and alters watercourses[3], which was introduced into Tierra del Fuego in 1946 with the aim of establishing a fur trade[4]. However, with a lack of natural predators, the beavers rapidly spread and have led to huge loss and degradation of the region's forests and peatlands, which have not evolved alongside the beaver[5]. Infrastructure has also been affected through flooding of highways and farmland, and have even led to the loss of telecommunication services[6].

There is often the assumption that nothing can be done to reduce the impacts from IAS, or that their management would be too costly. This is because action is often only considered once the IAS have become widespread and their impacts are obvious. However, nothing could be further from the truth. Society as a whole needs to focus efforts on prevention, and thereby protecting nature, human-wellbeing and economies from the future impacts resulting from the increasing numbers of IAS that are being transported around the world. There are many cost-effective measures that can be implemented to do this, such as border security checks on high-risk goods, surveillance for the early detection of new arrivals, and rapid response capacity to quickly remove IAS before they become established and spread. In addition, there is growing evidence that the eradication of IAS, especially in terrestrial environments, is becoming more feasible over larger areas including with the use of innovative approaches and novel technology[7]. We also know that some of the greatest conservation gains are realised through IAS removal, when compared to other conservation actions[8].

IUCN is working with its Commissions and Members to support society in addressing threats posed by IAS, primarily to help global efforts in achieving the Kunming-Monreal Global Biodiversity Framework’s Target 6 on IAS[9]. A recent development is the publication of the Convention on Biological Diversity (CBD) IAS Toolkit[10], produced by IUCN and the CBD secretariat, which guides countries on the measures needed to prevent the introduction of IAS, remove or mitigate their impacts, and the baseline information needed to prioritise actions. The toolkit also provides guidance on how countries can develop a National Invasive Species Strategy and Action Plan (NISSAP), which will ensure that the most cost-effective measures are implemented to address priority needs.

Addressing impacts from IAS, both current and future, is definitely feasible, we just need to take a whole-of-society approach and invest both resources and the political will to do it.